Blowing nozzle

ABSTRACT

An adjustable blowing nozzle comprising a central pipe through which fuel is fed, an outer pipe coaxially surrounding the central pipe through which an oxygen containing gas is fed under pressure, a plurality of flexible guide vanes extending in radial direction through the space between the central and the outer pipe, and means for adjusting the guide vanes between a position in which the same extends respectively in axial planes and a plurality of positions in which the guide vanes are twisted to a varying degree about the axis of the pipes to impart a whirling movement to the gas passing through the outer pipe. The outer pipe is preferably surrounded by a water jacket for cooling the blowing nozzle.

United States Patent [72] lm'entors Kazuo Konioka:

Takeshi Tada. both of Yohohama-shi, Kanagawa-ken. Japan [21] Appl. No 780,003 [22] Filed Nov. 29, 1968 [45] Patented June 22, 1971 [73] Assignee Nippon Kokan Kabushiki Kaisha Tokyo, Japan [54] BLOWING NOZZLE 1 Claim, 9 Drawing Figs.

152] US. Cl .1 239/4025, 239/1323, 239/487 [51] lnt.Cl BOSb 7/10 {50] Field ol'Search .1 239/1323, 487, 489, 402.5, 465, 481

[56] References Cited UNITED STATES PATENTS 2,844,408 7/1958 Dickmann et al 239/487 X 872,288 11/1907 Koons .1 239/1323 2,578,121 12/1951 Bailey 239/1323 X 3,236,281 2/1966 Bain et al 239/1323 X 3,266,552 8/1966 Denis 239/1323 X Primary Examiner-Lloyd L. King Attorney-Michael S. Striker ABSTRACT: An adjustable blowing nozzle comprising a central pipe through which fuel is fed, an outer pipe coaxially sur rounding the central pipe through which an oxygen containing gas is fed under pressure, a plurality of flexible guide vanes extending in radial direction through the space between the central and the outer pipe, and means for adjusting the guide vanes between a position in which the same extends respectively in axial planes and a plurality of positions in which the guide vanes are twisted to a varying degree about the axis of the pipes to impart a whirling movement to the gas passing through the outer pipe. The outer pipe is preferably surrounded by a water jacket for cooling the blowing nozzle.

PATENTED JUH22 IQYI SHEET 2 OF 3 BLOWING NOZZLE DETAILED EXPLANATION OF INVENTION This invention relates to blowing nozzle or burner to be applied to various refining and smelting operations and in particular, to the provision of a burner which properly regulates the combustion flame, stabilizes combustion in the case of feeding of a large volume of fuel, achieves a rapid smelting of a large quantity of cold charge when applied to a smelting device such as a converter or an open-hearth furnace or to various combustion equipments and which makes possible at all times an adequate operation under proper control corresponding to the form of a furnace or a combustion equipment and other operating conditions to bring about an improvement of operational efficiency.

In the operation of a converter, etc., nozzles for oxygen blowing are being widely adopted. Further, in such operation of a converter, etc., the practice of smelting a cold charge by means of an oxygen-fuel burner is frequently applied. In particular, for the purpose of smelting a large cold charge in a short time, it is necessary to feed a large volume of fuel and moreover, .it is important to obtain satisfactory combustion efficiency and a stable short flame irrespectively of the large volume of fuel supplied in that case. Generally, when the fuel is blown in by means ofa nozzle or a burner, it is indispensable for the securance of a stable and highlyefficient combustion to vary the fuel to charge or charge it in great quantities as required and to adjust the length of flame corresponding to the respective conditions of combustion, heat treatment or the form of combustion equipment, etc However, conventional burners of this type provide a satisfactory flame under certain conditions only, that is, they are designed according to certain standards and, when using such a burner and feeding fuel, for instance, in an amount exceeding the standard, unstable combustion and lowering of combustion efficiency are brought about. In a conventional system, different nozzles or burners have to be applied when the nozzle is used only for smelting the charge or when the nozzle is used also for refining the charge. Accordingly, for instance, when smelting cold charge and at the same time carrying out ordinary oxygen blowing, different nozzles should be available for the respective processes and the operation has to be carried out in exchanging these nozzles. This means an inevitable suspension of operation each time of such exchange and if one takes into account the progress of reaction or change, etc. during said suspension period, it is obvious that even if two or three nozzles or burners were made available, really desirable combustion or blowing meeting the respective operating conditions cannot be achieved. 7

This invention has been made as a result of studies to eliminate the abovementioned disadvantages of the conventional blowing nozzles that is, the principal object of this invention is to provide a blowing nozzle which permits feeding ofa large volume of fuel and yet ensures stable and highly efficient combustion when smelting a great amount of cold charge in a converter, etc. For this purpose, according to this invention, twisting guide pieces or guide vanes are provided in ajet pipe for oxygen or oxygen-enriched air, etc. arranged in the form of a concentric circle about a center fuel supply pipe jetting heavy oil, so that the gas stream emitted from the jet pipe is given a whirling movement, and, an appropriate back current region is formed in a flame by such whirling movement of oxygen, etc. and such back current region effects a flame-holding function to produce a stable and relatively short flame with high combustion efficiency with respect to a large volume of fuel charge, as a result of which even a high load of cold charge, such as solid pig iron and scrap, can be smelted in a short time and the tonnage of steel output per unit time in an open-hearth furnace, etc. can be increased.

Another object of this invention consists in making possible along with the attainmen'tof the above-mentioned principal object, the adjustment and setting as required of the rotating degree of the guide piece in the aforesaid jet pipe of oxygen or oxygen-enriched air, etc., thereby forming a rational flame in freely regulating the above-mentioned whirling effect and the corresponding back current region as well as the flame-holding function, thus causing a single lance or blowing nozzle to serve satisfactorily for a quite extensive range of application as an oxygen blowing lance for converter as well as a burner for smelting of various cold charges. According to the present invention, at least one of the above-mentioned jet pipes of oxygen or air is turnable about its axis and the ends of the aforementioned guide pieces are fixed in between the walls of such pipes and, in the case of adjustment, the turnable pipe is turned to adjust and change the degree of twist of said guide pieces.

A further object of this invention is to obtain a blowing nozzle which permits to carry out the above-mentioned adjustment and change of the twist degree of the guide pieces in a simple manner. For this purpose, according to this invention a rotary pipe surrounding a center jet pipe is provided in an outer pipe, twistable guide pieces are mounted between such rotary pipe and outer pipe and a rotary piece projecting out of the outer pipe is fixed to the bottom end of such rotary pipe. In this way, the aforementioned adjustment of the degree of the guide piece twist can be made simply and smoothly on the rear end of the outer pipe and jet conditions always corresponding to the operating conditions can be brought about.

Another object of this invention consists in providing a blowing nozzle by means of which the aforesaid adjusting process can be achieved smoothly and which will not be liable to breakage or damage. A guide piece having a freely adjustable degree of twist, can be made of a material possessing flexibility such as rubber, etc., but in the case of such type of blowing nozzle to be utilized generally by insertion into a red hot furnace, even on the assumption of water cooling of its exterior, a material possessing proper heat resistability is desirable and therefore a piece of steel or the like is usually employed but flexibility cannot be expected of such a piece of steel. Moreover, if such a guide piece not possessing flexibility is twisted, its length in the axial direction cannot but change continuously, thus stressing the guide piece excessively.

According to this invention, the aforementioned rotary piece of the rotary pipe and a flange on the outer pipe are screwed together and the pitch of the screw threads is so designed as to match expansion or contraction of the guide piece due to twist. In this way, if the rotary piece is turned to adjust degree of twist, of the guide pieces, the rotary pipe moves axially relative to the outer pipe and absorbs axial expansion or contraction of the guide pieces die to a change in twist degree, resulting always in a smooth adjustment, without causing any damage of the guide pieces and other parts.

The characteristics or effects of this invention can be best understood from the following description of specific embodiments when read in connection with the accompanying drawings in which FIG. 1 is an axial sectional view of the nozzle according to this invention;

FIG. 2 is a partial view similar to FIG. 1 showing the guide vanes and mechanism components in untwisted position;

FIG. 2a is a front view of the vanes in untwisted position;

FIG. 2b is a rear view view of the turning mechanism;

FIG. 2c is a partial sectional view of a modification of the rotary pipe;

FIG. 3 is a partial view similar to FIG. 2 and showing the guide vanes in twisted position and;

FIG. 3a is a front view of the vanes in twisted position;

FIG. 3b is a corresponding rear view of the turning mechanism;

FIG. 4 is an explanatory drawing of the whirling condition of oxygen flow and fonnation of a back current region.

An embodiment of this invention will be described with reference to the above-mentioned drawings. The blowing nozzle according to the present invention comprises, as shown in FIG. 1, the central pipe 1 adapted to be connected at its rear end, shown in FIG. I as the right hand of the pipe, to a supply of fuel such as heavy oil, not shown in the drawing, so that such fuel may be fed through the interior of the central pipe I. An outer pipe 3 coaxially surrounds the central pipe 1 radially spaced from the latter. The front end, shown in FIG. 1 as the left end of the outer pipe, tapers slightly towards the outer surface of the central pipe 1 to form in the region of the front end of the latter a throat 23, while the inner surface of the outer pipe extending beyond the throat flares slightly outwardly as shown at 24. A curved pipe member 9 is connected, in a manner as will be described in detail later on to the rear or right end of the outer pipe 3 and the free end of the curved pipe 9 is adapted to be connected to supply of a combustion sustaining gas, such as air, air enriched with oxygen, or pure oxygen under pressure, not shown in the drawing. The central pipe 1 extends through a branched pipe fixedly connected to the curved pipe 9 and a stuffing box of conventional construction is connected to the outer end of the branched pipe to prevent escape of gas under pressure through the clearance between the central pipe and the branched pipe. A rotary pipe 2 is coaxially arranged with very small clearance about the central pipe 1 and a plurality of angularly displaced flexible guide vanes 11 extend between the front end of the rotary pipe and the inner surface of the outer pipe 3. Each of the guide vanes 11 is fixedly connected, for instance by welding, at its front end at 17 to the outer pipe 3 and at its rear end at 18 to the rotary pipe 2. The flexible guide vanes II are preferably formed from spring steel. The rotary pipe is turnable about its axis to thereby adjust each of the guide vanes 11 between a first position in which these guide vanes respectively extend in planes including the axis of the rotary pipe and a plurality of twisted positions in which the guide vanes 11 are twisted to a varying degree about the axis of the rotary pipe. To turn the rotary pipe about its axis, an annular member 12 of substantially T-shape cross section is connected by means ofa plurality of radially extending webs 21 (FIG. 2 and FIG. 2b) to the rotary pipe 2, and this annular member 12 is located between the rear end of the outer pipe 3 and the corresponding end of the curved pipe 9. A pair of flange members 13 and I4 are respectively fixedly connected to the facing ends of the outer pipe 3 and the curved pipe 9 and the hub of the flange member 13 fixed to the outer pipe 3 is provided on its peripheral surface with a screw thread 20, whereas the annular member I2 is provided on its inner peripheral surface with a corresponding screw thread l9 which is threadingly engaged with the screw thread so that by turning the annular member 12, the rotary pipe 2 may be turned about its axis imparting thereby a twisting movement to the guide vanes 11 so that the latter will be twisted to a varying degree about the axis of the rotary pipe.

Since during twisting of the guide vanes II from the straight planar position as shown in FIG. 2 to the twisted position as shown in FIG. 3, the axial length of the guide vanes will be reduced, and since each of the guide vanes is fixedly connected at its front end to the outer tube 3, the rotary pipe has to be shifted in axial direction through a corresponding distance and to accomplish this corresponding axial shifting of the rotary pipe, the pitch of the screw threads 19 and 20 is made in such a way that during turning of the annular member 12, and the rotary pipe connected thereto, the latter will be shifted in axial direction for a distance corresponding to the shortening of the axial length of the guide vanes 11 during the twisting thereof. On the other hand, the rotary pipe may be made out of two members 2 and 2' as shown in FIG. 20 which are respectively provided at the facing ends with longitudinally extending grooves 2a in which corresponding tongue portions of the two members of the rotary pipe extend so that the two members are connected to each other for simultaneous rotation while being axially shiftable with respect to each other.

The two flange members 13 and 14 are fixedly connected to each other by a spacer bolt I6, as shown in FIG. 1, which keeps the adjacent ends of the outer pipe 3 and the curved pipe 9 spaced from each other to permit axial shifting of the annular member 12 sandwiched therebetween. A radially extending handle 22 is preferably fixedly connected in the manner as for instance shown in FIG. 2 to the annular member 12 to facilitate turning of the same about its axis.

The rotary pipe 2, the annular member 12 connected thereto together with the handle 22, forms therefore means connected to the guide vanes 11 for adjusting the position of the same between a first position in which the flexible guide vanes extend in planes including the axis of the central pipe I and a plurality of second positions in which the flexible guide vanes are spirally twisted about the axis of the central pipe 1 thereby impart a gas passing through the space between the outer surface of the central pipe and the inner surface of the outer pipe 3 a whirling movement as indicated in FIG. 4. The guide vanes 11 serve also to maintain the outer pipe 3 and the central pipe 1 in proper coaxial relationship.

The blowing nozzle of the present invention preferably includes also a water jacket surrounding the outer pipe 3 and this water jacket preferably comprises an inner tubular member 5 surrounding the outer pipe and an outer tubular member communicating at the front end of the outer pipe with the inner tubular member, to define between the two tubular members annular passage ways 6. Cooling water inlet means 7 and cooling water outlet means 8 respectively communicate with the rear ends of the aforementioned passages 6 so that cold cooling water may be fed into the inner tubular member 5 to flow through the inner passage 6 along the surface of the outer pipe 3 towards the front or left end of the latter and to return through the outer passage 6 to the discharge passage 8.

By twisting the guide vanes 11 to a predetermined degree, it is possible to impart to the gas passing under pressure through the space 4 between the outer surface of the rotary pipe 2 and the inner surface of the outer pipe 3, a rotary velocity which is equal to the axial velocity of the gas under pressure passing through the space 4. Thereby a small back-current region I is formed, as shown in FIG. 4 in the jet fluid emanating from the end of the outer pipe 3. This back-current region can be progressively enlarged by increasing the turning angle of the rotary pipe to a back-current region II, likewise shown in FIG. 4. A flame produced by igniting the mixture of fuel and combustion sustaining gas emanating from the end of the nozzle, can be shortened in dependence on the size of the back current thus produced so that even if large amounts of fuel are fed through the central pipe 1, a relative short and stable flame may be produced and an excellent combustion efficiency may be obtained.

Such a flame makes possible a rapid smelting of even a high load of cold charge and can increase the tonnage of steel output per unit time in the case of an open-hearth furnace too and moreover, it can be freely changed depending on the respective operating conditions such as furnace body conditions, cold charge load condition and smelting condition, etc., making it possible to secure a highly efficient operation and eliminating, the necessity of lance or nozzle exchange. According to this invention, the shape of flame can be changed properly corresponding to the respective operational requirements, a stable flame excellent in combustion efficiency is formed even in the case of a large volume of fuel charge, etc. and ensures a stable highly efficient operation, and moreover a single burner can be adjusted and utilized as desired for an extensive range of applications as, for instance for cold charge smelting and as a blowing lance for a converter and so on. Further, as a whirling gas current as mentioned above hits against a molten metal surface in an open-hearth furnace or a converter, it will provide a stirring effect on the molten metal which can be adjusted, thus further improving the reactions in a furnace and realizing uniform reaction in a short time. On the other hand, it is also possible to charge, as required, fluxing agents or additives in a powdery or granular form through the central pipe 1.

We claim:

l. A blowing nozzle comprising a central pipe having a front end and a rear end adapted to be connected to fuel supply; an outer pipe coaxially fixed to and radially outwardly spaced from said central pipe and having a front end projecting beyond said front end of said central pipe and a rear end adapted to be connected to a supply of and oxygen-containing gas under pressure; a plurality of flexible guide vanes extending angularly spaced from each other in substantially radial direction through the space between said outer and said central pipe rearwardly of the front end of the latter and each connected at one end thereof to said outer pipe; and connected to said guide vanes for adjusting the same between a first position in which said flexible guide vanes extend in planes including the axis of said central pipe and plurality of second positions in which said flexible guide vanes are spirally twisted about said-axis to impart to the gas passing through said space a whirling motion, said means comprising a rotary pipe coaxially arranged with small clearance about said central pipe and connected to the other end of each of said guide vanes, and turning means connected to the rear end of said rotary pipe, said turning means comprising a first annular member fixed to the outer pipe in the region of said rear end thereof and a second annular member fixed to said rotary pipe, one of said annular members being provided at the outer peripheral surface thereof with a screw thread and the other of said annular members being provided at the inner peripheral surface thereof with a screw thread threadingly engaged with said screw thread on said one annular member, said screw threads having a pitch so that said second annular member will he axially shifted during turning thereof in one direction for a distance corresponding to the axial shortening of said flexible guide vanes during twisted thereof. 

1. A blowing nozzle comprising a central pipe having a front end and a rear end adapted to be connected to fuel supply; an outer pipe coaxially fixed to and radially outwardly spaced from said central pipe and having a front end projecting beyond said front end of said central pipe and a rear end adapted to be connected to a supply of and oxygen-containing gas under pressure; a plurality of flexible guide vanes extending angularly spaced from each other in substantially radial direction through the space between said outer and said central pipe rearwardly of the front end of the latter and each connected at one end thereof to said outer pipe; and connected to said guide vanes for adjusting the same between a first position in which said flexible guide vanes extend in planes including the axis of said central pipe and plurality of second positions in which said flexible guide vanes are spirally twisted about said axis to impart to the gas passing through said space a whirling motion, said means comprising a rotary pipe coaxially arranged with small clearance about said central pipe and connected to the other end of each of said guide vanes, and turning means connected to the rear end of said rotary pipe, said turning means comprising a first annular member fixed to the outer pipe in the region of said rear end thereof and a second annular member fixed to said rotary pipe, one of said annular members being provided at the outer peripheral surface thereof with a screw thread and the other of said annular members being provided at the inner peripheral surface thereof with a screw thread threadingly engaged with said screw thread on said one annular member, sAid screw threads having a pitch so that said second annular member will be axially shifted during turning thereof in one direction for a distance corresponding to the axial shortening of said flexible guide vanes during twisted thereof. 